Stoker mechanism



A ril 20, 1937. H. L. KRAEFT STOKER MECHANISM Filed Jan.'4, 1935 4 Sheets-Sheet l April 20, 1937. H. 1.. KRAEFT STOKER MECHANISM 4 Sheets-Sheet 2 Filed Jan. 4, 1933 llZb V GUM/Maw April 20,, 1937. H. KRA'EFT STOKER MECHANISM Filed Jan. 4, 1933 4 Sheets-Sheet 3 A il 20, 1937.

H. 1.. KRAEF T STQKER MECHANISM Filed Jan. 4, 1933 4 Sheets-Sheet 4 Patented Apr. 20, 1937 UNITED STATES PATENT OFFICE STOKER MECHANISM Application January 4, 1933, Serial No. dtilflltt 3 Claims.

39 More specifically, my invention is directed to ersed the fuel. in an even mariner over the fire ed when the fuel is presented to the fire door of the fumace Toy associated Stoker mechanism and which will be efficient regardless of variations in burning characteristics of fuel being tied to tire teed.

objects of my invention will hereinafter lcecoine rent from the following description, cis to the accompanying drawings and illustrate a preferred embodiment thereoi ll! association with a fuel feeding mechanism hopper of the so-called overfeed Stoker type. The essential characteristics of the in ventio are or orized in the claims.

ogs, Fig. l is a longitudinal section embodying the features or" my 4 is a cross-section, looking toward e door frame of a furnace, equipped with my ration corresponding to the lines 22 in l cg. 3 is a cross-sectiorial view, taken uel flipper means, comprising part of ch olsm and corresponding to the lines 1; Fig. ils an enlarged cross-sectional dries 3-4 of 5; Fig. 5 is a horisorital section taken through part of the housing -ll of l; r g. 6 is an enlarged crossof a fuel flipper member and associated i'uel guiding means taken substantially along the lines of ,0; Fig. l is an enlarged view oi the fuel flipper mechanism; a? is an enlar ed cross-sectional detail of a mechanism; Fig. 9 is a transverse section town t rough the stolier gear drive'substantially along the line fi-t of Fig. l and lulu. id is a persgcective a fuel escape ledge.

El y invention contemplates the use or" a rotary element having peculiar characteristics of design, which function to act upon coal particles es some escape from afeed tu' e positioned in the fire door of a furnace and the purpose is to provide a mechanism which will be emcient in its functioning in spreading fuel particles by he provision of ameclianism which will serve to cart of a hearing mechanism and takenv flipping the same over the firebed, regardless of the type of mechanism which is utilized to present the fuel to the fire door, and I propose to use an associated housing mechanism in the form oi a fire door stoker adapter, which will protect the rotary element and its bearings from attendant heat reflected from the fire pit of the furnace. I arrange this rotary element and its adapter housing in such manner that the rotary element can always be positioned in definite relation to the fire pits of furnaces, regardless of variations in furnace designs, and particularly the variations oi the width of the fire door frame. This rotary element can be driven at any desired speed which will meet. the fuel spread requirements of grate areas oi furnaces of dif ierentdeslgus. The adapter housing and rotary Referring to the drawings, and particularly to screw conveyor it is suitably rotatably mounted on bearings 22 and 2%, comprising part of the frame structure oi the Stoker mechanism and. is rotated by a worm gear 25, the worm gear ice ing driven by a worm 26 carried Toy a transversely extending shaft ill. The shaft ll is rotataloly mounted in suitable bearings comprising part of the stoker frame. The worm shaft El carries a gear which is driven by a gear the latter "gear being mounted upon a small stud shaft til and the gear being attached to a sprocket wheel 85', which is driven by sprocket wheel 332 mounted upon shaft of a motor 36 adjustably attached at to the underside of the stoker frame. A driving chain it serves to connecttlie two sprocket wheels 33 and The stolrer frame may he supported in any suitable manner, such as an overhead suspension, attached to the ceiling of the furnace room or upon a frame resting upon the floor in front of the fumace.

The fuel flipper mechanism, the manner of mounting the same within the adapter and housing mechanism, and the relation of the adapter mechanism to the fuel feeding mechanism of the hopper will now be described.

- A rotary fuel flipping or impelling element 59 is shown as being mounted upon a shaft 5|, the element being disposed to rotate on self-aligning bearing mechanism generally indicated at 52 and 53, (see Figs. 1, 2, 3, and 5) and this rotary element, with attendant bearing mechanism, is supported within a housing in such manner that the shaft 5| of the rotary element extends across the door opening, with the rotary element disposed adjacent the fire pi. edge 55, (see Fig. 1),of the furnace and in the lower part of the door opening.

The housing construction issuch that the upper part thereof forms a passageway for the passage of fuel from the fuel feeding means toan adjustable ledge member 60, the function of which will be hereinafter described. The housing comprises a box-like structure, of comparatively open construction as viewed from the front of the furnace, but arranged to enclose the bearing mechanism supporting the fuel-flipper 50, when viewed from the fire side thereof. Hence, this construction may comprise a bottom panel 62, secured to the side panels 63 and 64, in any convenient manner, such as welding, the side panels 63 and 64 being similarly attached to a top panel member 65. The inner or fire side of the housing structure comprises a metallic panel 68, suitably secured to thetop, bottom and side panels just described, and this fire side panel is provided with a rectangular opening, the width of which is substantially equal to the length of the rotatable flipper member 50. An extension on the fuel-feeding tube I2 is provided, comprising'a metallic member 10, which, in the present instance, is round at the outer end thereof to telescopically fit the inner'end of the fuel-feeding tube l2, at a point which is exterior of the fire door frame of the furnace, as shown in Fig. 1, while the inner end 10a of the tube is flared to a rectangular shape, (see Figs. 1 and 2) whereby the inner rectangular opening thereof will have a width substantially equal to the length of a the fuel flipper 50 and the height substantially corresponding to the diameter of the fuel feed tube l2. It will be apparent, from Fig. 2,'that this width is substantially less than the width of the housing structure to afford a support and a housing for the bearing mechanisms 52 and 53 and to afford room for a sprocket wheel 18, mounted upon the fiipper shaft 5|. I provide two inner vertically disposed panel walls and 8!, which extend from the top panel member 65 to the bottom panel 62, and which are spaced apart a distance substantially equal to the length of the flipper 50, and the inner fuel discharge width of the tube 10.

To completely close the space between the housing for the fuel feeding mechanism and the walls of the fire door of the furnace when the apparatus is in operative'position, I provide a shell structure in sliding engagement with the bottom panel 62, top panel 65, and side panels 83 and 64, comprising top and bottom members, 88 and 89, respectively, and side panels 90 and 9|, which are flanged to engage a closure panel 92 (see Fig. 2) which may be of sufficient dimensions to close the largest furnace door opening by contacting-with the outer edge thereof. The inner housing panels 62 and 63, 64 and 65, and the outer panels 89, 9|, 90 and 88 are in respective sliding or telescopic engagement. It will thus be apparent that the inner fire front panel 69 of the housing is adjustable toward and away from the panel 92 to meet various depths of fire door frames while at all times permitting fire pit edge 55 in the relation shown. Any suitable means may be used to secure the housing panels in adjacent position,'such as bolts 200 secured to the panel members 68 and extending through horizontally extending slots 90a and 9 la formed in the panel members 999l and exteriorly disposed wing nuts 20l in threaded engagement with the bolts (see Fig. 5).

The rotary flipper 50 is driven from the worm shaft 21 'by reason of the sprocket wheel '18 being driven by a chain 95, the chain 95 extending to and over a sprocket wheel 96 mounted on the worm shaft 21 at the forward end of the stoker mechanism.

The purpose and shape of the contour of the flipper will now be described. In the present design the diameter of the flipper 50 is about three and one-half inches and the length about six inches. Upon the circumferential surface are formed four equidistantly spaced impeller ridges I00, comprising radial surfaces In! at the end portions of the flipper and centrally disposed forwardly converging surfaces I02, which function as a sort of a wedge to impart to fuel particles falling over the forward edge of the ledge 60 a fire bed spreading movement. A semi-cylindrical housing I08 partially encloses the flipper 50. The

lefthand side of this housing (Fig. 6), is provided with a flange 18a which slopes toward the firebed and is engaged by a similar flange "18b which is attached to the housing panel 62. It will be apparent that by adjusting the edge 60a, of the ledge 60, in a tangential direction relative to the circumferential path of movement of the flipper 50, a considerable range of regulation of the flipping action of the flipper 50 upon the fuel particles, as the latter fall over the edge 60a, is obtainable; It will also be apparent that the housing arrangement of the flipper 50 is such that fuel particles cannot fail to a place of rest adjacent the firebed. Fire hazards thus are eliminated, particularly when the stoker mechanism is not in operation, and there is a fire in the furnace.

The bearing mechanism for the flipper shaft 5| is constructed in such manner as to be practical under comparatively high temperatures, due

to heat radiance from the fire pit and conduction of the metallic parts comprising the flipper and the housing. Accordingly, I arrange this bearing mechanism in such manner as to be also operative should the various metal panels comprising the housing warp. Hence, the bearing mechanism may comprise a block of hard graphite H3 encased in spherically formed retainers III, which bear in a bearing bracket I I2, secured to the housing panel 62, and having upper flanged portions 2a and 2b, shaped to be complementary to the spherical surface of the graphite retainer III, to loosely engage the same-whereby the bearings H3 may float in the brackets. The retainers Ill and the graphitic blocks carried thereby are slotted in the upper parts thereof to receive sticks of lubricating graphite H5, and I provide slidable weights H6 to bear upon the upper projecting ends of the lubricating graphite blocks H5 to thus maintain the lubricatingness or coarseness of the fuel which is being fed by the apparatus to the furnace. To facilitate such adjustment, the ledge 60 is provided with two downwardly extending flanges 80b, which are slidably mounted on the inner vertical walls 8ll8l of the housing structure. A clamping bar I30, having one end threaded to receive a clamping nut l3l, is disposed within a tube I32 of a length to abut the inner faces of the flanges 60b and passes through elongated openings or slots 800 in the flanges. It will be thus apparent that the ledge 60 can be slidably adjusted relative to the rotary flipper in a convenient manner, without necessitating any disorganization of theelements of the housing structure.

From the foregoing it will be apparent that I have provided a fuel spreader mechanism, arranged in a very compact manner for adaptation to stoker mechanisms of various mechanical types and which will function to deliver coal to a fire door whereupon my invention will be quite efficient in the application of the fuelparticles to the fire bed. This mechanism is arranged in such manner that it is readily adaptable to fur-' naces of varying designs, that is, furnaces with fire pits or fire boxes of different shapes, such as square, round and rectangular or elongated. Structural variations ofthe fire door frame are met by the ready adaptability of the housing structure and coal passageways of the device, whereby the fuel is caused to enter at the upper part of the fire door and thereafter caused to be flipped to the fire bed without undue agitation thereof. Variations in fuel characteristics are met by the adjustability between the relationship oi the fuel spreader or flipper mechanism and the fuel passageway in that the adjustable ledge I provide is such as to function in controlling the falling movement of the fuel particls relative to the circumferential path of movement of the fuel spreading means. The

construction is .such that any external obstruc;

tion about the furnace installation need not be a serious detriment to a quick installation -of a stoker mechanism used in association with my invention, in that the ultimate position of the stoker mechanism proper relative to the fuel spreading means is adjustable throughout a considerable length, which adjustments do not in any manner interfere withthe efficient positioning of the fuel spreader means relative to the flrepit of the furnace. All of this I accomplish by incorporating my mechanism in a housing which may be of such construction as to be quite economically manufactured; the construction may be light and formed of heat resisting sheet metal,

and the arrangement is such that when the stoker mechanism is shifted to fuel feeding position relative to the furnace fire door the fire door opening is completely closed while the fuel spreader mechanism is positioned within the fire door frame immediately adjacent the fire bed.

Radiant heat influences of the fire bed upon the mechanism are oflset through external ventilation by reason of the open construction of the housing as viewed from the front of the furnace.

Protracted experimenting has proved that the device is highly efiiclent in spreading the fuel over the firebed when proper adjustments are made to meet the particular firebed environment. The loss of the finer fuel particles up the stack before complete combustion is avoided and the usual fire hazards-incident to the use of overfeed stokers which are automatically operated by thermostatic control over considerable periods of time without observation are avoided.

I claim:

1. In a stoker of the overfeed type, the combination of a fuel delivery tube adapted to extend into a fire door opening, a rotary element adapted to be disposed within the fire door opening adjacent the fire. pit edge thereof, means for forcing fuel through said tube and means for driving said rotary member, a housing construction supporting the rotary member in cooperative relation to the tube, and a second housing surrounding the first-named housing and com-.

the first-named housing and the fire door' wall when the housings are in o erative position rela-. tive to the fire door opening, said first-named housing being relatively adjustable longitudinally of the tube whereby the position of the rotary egement may be adjusted relative to said fire pit e ge.

2. The combination with a furnace having a fire door opening of an overfeed stoker, comprising a substantially horizontal fuel conveying tube with a transverse cross-sectional area substantially less than the fire door opening of the furnace, a housing disposed within the door opening connected in telescopic and adjusted relation with said tube, a rotary fuel spreader carried by said housing within said door opening, a second housing for closing the space between the walls of the first housing and the walls of the fire door opening, said second housing being fire door frame, of an overfeed stoker comprising a substantially horizontal fuel conveying tube, a housing mounted within the fire door frame, a rotary fuel spreader carried by said housing, a second housing comprising a closure for the space between said housing and the walls of the fire door frame, said first housing having a telescopic connection with said second housing, whereby the fuel spreader may be adjusted toward and away from the fire pit edge, an extension for said tube telescopically arranged relative to said tube and said first-named housing whereby the length of said tubemay be adjusted relative to the ifuelspreader and means 7 to progress fuel through said tube and to operate said rotary spreader.

HERMAN L. KBAEFI. 

